Abstract In recent years, 20% of mangroves have been lost to deforestation worldwide. Mexico is one of the countries with the greatest loss in mangrove surface area, contributing to CO2 emissions and promoting climate change. However, knowledge about the factors that influence the loss and gain in mangroves, CO2 emissions, and the dynamics of land use and vegetation cover at local and regional scales is lacking. Therefore, the objectives of this study were to analyze land use dynamics in the Marismas Nacionales area (Mexico) from 1981 to 2015, to determine the rate of mangrove deforestation and annual degradation, and to estimate the CO2 emissions derived from these processes using geographic information system techniques. To determine land use changes, we used the cross-tabulation matrix and obtained various change parameters that allowed generating an equation to estimate the rates of deforestation and degradation. We used data from the National Inventory of Emissions of Greenhouse Gases and Compounds (Mexico) to estimate CO2 emissions and absorptions (equivalent, CO2e) prompted by mangrove deforestation, degradation, reforestation, and natural recovery. For the 1981-2005 period, the emissions estimate was 432.50 Gg of CO2e due to the annual mangrove deforestation rate of 0.77%, and degradation was 27.16 Gg of CO2e, with an annual rate of 7.64%. For the 2005-2015 period, the emissions estimate was 145.21 Gg of CO2e due to an annual deforestation rate of 0.44%, and degradation was 24.80 Gg of CO2e, with an annual rate of 4.94%. The greatest mangrove loss was due to transformation into land in the agricultural-livestock and anthropic development categories. Degradation was due to natural phenomena and anthropogenic activities.

Resumen En los últimos años, se ha deforestado el 20% de manglar a nivel mundial. México es de los países con mayor pérdida de superficie de mangle, algo que contribuye a las emisiones de CO2 e impulsa el cambio climático. Sin embargo, falta conocimiento sobre los factores que influyen en la pérdida y la ganancia del manglar, las emisiones de CO2, y la dinámica de usos de suelo y cobertura vegetal a escala local y regional. Por tanto, los objetivos de este estudio fueron analizar la dinámica de uso de suelo en la zona de Marismas Nacionales (México) durante el periodo 1981-2015, determinar la tasa de deforestación y degradación anual del manglar y estimar las emisiones de CO2 derivadas de estos procesos utilizando técnicas de información geográfica. Para determinar los cambios de uso de suelo, con la matriz de tabulación cruzada, se adquirieron diversos parámetros de cambio que permitieron generar una ecuación para estimar la tasa de deforestación y degradación. Con los datos del Inventario Nacional de Emisiones de Gases y Compuestos de Efecto Invernadero (México), se estimaron las emisiones y las absorciones de CO2 (equivalente, CO2e) promovidas por deforestación, degradación, reforestación y recuperación natural de manglares. Para el periodo 1981-2005, la emisión estimada fue de 432.50 Gg de CO2e debido a una tasa anual de deforestación del 0.77%, y la degradación fue de 27.16 Gg de CO2e a una tasa anual de1 7.64%. Para el periodo 2005-2015, la emisión fue de 145.21 Gg de CO2e debido a una tasa anual de deforestación del 0.44%, y la degradación fue de 24.80 Gg de CO2e a una tasa anual del 4.94%. La mayor pérdida de manglar se debió a la transformación a suelos con categorías de agrícola-pecuario y desarrollo antrópico. La degradación sucedió por fenómenos naturales y actividades antropogénicas.

Abstract The objective of this research was to study deforestation and its causes in the state of Sinaloa, Mexico. Using mapping of land use and vegetation in 1993 and 2011 at a scale of 1: 250 000, deforestation was estimated through a technique of detecting changes, and then characterized by consulting experts. Finally, a matrix of change was applied to analyze the losses, gains and transitions and to corroborate cartographically the results obtained by the experts and the detection of changes. The results indicate a deforestation of 126.50 km2/year and an average annual rate of 0.41%. The consultation of experts determined that the main causes of these processes are agricultural expansion and extension of infrastructure, with impacts of 49.40% and 18.8%, respectively. The matrix of change showed that the particular category of rainforest lost 2374.19 km2, on the contrary, seasonal agriculture also increased by 3326.62 km2 and human settlements increased from 191.51 km2 to 623.28 km2.

Resumen El objetivo de esta investigación fue estudiar la deforestación y sus causas en el estado de Sinaloa, México. Para ello, se utilizó la cartografía de Uso de Suelo y Vegetación del año 1993 y 2011 a escala 1:250 000, con esta se estimó la deforestación mediante una técnica de detección de cambios; posteriormente, se caracterizó la deforestación mediante la consulta a expertos. Por último, se aplicó la matriz de cambios para analizar las pérdidas, ganancias y transiciones y corroborar cartográficamente lo obtenido por los expertos y la detección de cambios. Los resultados indican una deforestación de 126.50 km2/año y una tasa media anual de 0.41%. De la consulta a expertos se determinó que las principales causas de estos procesos son la expansión agrícola y la extensión de infraestructura con un impacto de 49.40% y 18.8%, respectivamente. En cuanto a la matriz de cambios, se determinó que especialmente la categoría de selvas perdió 2374.19 km2, por el contrario, la agricultura de temporal también se extendió 3326.62 km2 y la categoría de asentamientos humanos pasó de tener 191.51 km2 a 623.28 km2.

Um procedimento simples, rápido e preciso de cromatografia líquida de alta eficiência (HPLC) foi desenvolvido para a determinação de oxadiazona em formulações concentradas de pesticidas emulsificáveis. 20 µL de amostra, diluída em acetronitrila, foram injetados em uma coluna Kromasil C18 (250 × 4,6 mm, 5 µm), usando acetonitrila:água (80:20) como fase móvel, numa velocidade de fluxo de 1 mL min-1. Oxadiazona foi determinada por medidas de absorbância a 292 nm. Obteve-se, usando-se o procedimento desenvolvido, um limite teórico de detecção de 0,02 µg mL-1, um limite de quantificação de 0,047 µg mL-1, correspondendo a 0,02 e 0,07% m/v na amostra original e desvio padrão relativo de 0,08%, para três análises em replicata de amostras contendo 25% m/v de oxadiazona. A precisão do método foi evidenciada pelas porcentagens de recuperação de 98% a 99% para amostras contendo 0,015 a 0,085 mg de oxadiazona, assim como pela comparação entre os resultados encontrados pelo procedimento recomendado e pela espectrofotometria de infravermelho com transformada de Fourier (FTIR), para amostras reais de produtos formulados.

A simple, fast and precise high performance liquid chromatographic (HPLC) procedure has been developed for the determination of oxadiazon in emulsifiable concentrated pesticide formulations. 20 µL of diluted sample in acetonitrile were injected in a Kromasil C18 (250 ×am injetados em uma coluna Kromasil C18 4.6 mm, 5 µm) column, using acetonitrile:water (80:20) as mobile phase at 1 mL min-1 flow rate and oxadiazon determined by absorbance measurement at 292 nm. A theoretical limit of detection of 0.02 µg mL-1, a limit of quantification of 0.047 µg mL-1, corresponding to a 0.02 and 0.07% m/v in the original sample, and a relative standard deviation of 0.08% for three replicate analysis of samples containing 25% m/v. Oxadiazon were achieved using the developed procedure. The accuracy of the whole method was evidenced by recovery percentages from 98% to 99% for samples spiked with 0.015 to 0.085 mg oxadiazon as well as by the good comparability between results found by the recommended procedure and by Fourier Transform Infrared (FTIR) spectrophotometry for actual samples of formulated products.

Foi desenvolvido um método simples usando Infra-Vermelho com Transformada de Fourier (IRFT) para a determinação de Imidaclopride em formulações pesticidas. As amostram foram diluídas com CHCl3 e os espectros de IRFT de amostras e padrões foram obtidos numa resolução nominal de 4 cm-1, entre 4000 e 900 cm-1, com acumulação de 25 espectros. A determinação de Imidaclopride foi feita medindo-se tanto a área do sinal obtido entre 1577 e 1567 cm-1 ou a altura do sinal a 1572 cm-1, ambos com correção de linha base horizontal a 1900 cm-1. Os limites de detecção atingidos da ordem de 9 µg g-1, foram apropriados para a determinação de Imidoclopride em formulações comercias disponíveis. Os resultados com IRFT forma estatisticamente comparáveis àqueles encontrados para Cromatografia Líquida de Alta Performance (HPLC). O procedimento desenvolvido reduz o consumo de solventes orgânicos por preparação de amostra, de 53 mL de CH3CN requeridos com HPLC para 2,5 mL de CHCl3, reduzindo o descarte gerado, e aumenta a freqüência de medidas de 10 para 60 amostras h-1, quando comparado ao método de referência usando HPLC-UV.

A simple method has been developed for Fourier Transform Infrared (FTIR) determination of Imidacloprid in pesticide formulations. Samples were diluted with CHCl3 and the FTIR spectra of samples and standards were obtained at a nominal resolution of 4 cm-1 from 4000 to 900 cm-1 accumulating 25 scans. Imidacloprid determination was based on the measure of either peak area from 1577 to 1567 cm-1 or peak height at 1572 cm-1, both corrected using a horizontal baseline defined at 1900 cm-1. The limits of detection achieved, of the order of 9 µg g-1, were appropriate for the determination of Imidacloprid in commercially available formulations. FTIR results were statistically comparable to those found by High Performance Liquid Chromatography (HPLC). The procedure developed reduces organic solvent consumption, per sample preparation, from 53 mL CH3CN required for HPLC to 2.5 mL CHCl3, and reduces waste generation also increasing the sample measurement frequency from 10 h-1 to 60 h-1 as compared with the HPLC-UV reference method.